Objects may be placed into or removed from the cargo bed of a vehicle such as a pick-up truck or an open-topped trailer either by lowering a tail gate at the rear of the bed or by reaching over the upper edge of the side walls of the bed. Both of these options are somewhat inconvenient and/or awkward in certain circumstances. Since objects carried loosely in the bed tend to migrate toward the front of the bed when the truck is driven, they often can not be reached by a person standing on the ground behind an open tail gate. Accordingly, the objects may only be reached by climbing up into the bed or by reaching over the side walls. Attempting to lift items into or out of the bed over the side walls is difficult for all but the tallest of persons, and has the potential to cause injury to the back or other parts of the body.
Many owners/operators of pick-up trucks fit the cargo bed with a cover or a cap to protect the load from inclement weather and/or theft, thus making the bed even less accessible. The term "cover," as used herein, refers to a sheet of flexible material such as canvas that is pulled taught over the top of the cargo bed. Covers are Typically attached to the bed by snap fasteners, or by tie-down straps or ropes. The term "cap", on the other hand, refers to a rigid structure having sides and a roof and that extends above the walls of the bed. A cap is typically clamped or bolted to the bed walls on which it rests. With either a cover or a cap in place on the truck bed, the tail gate provides the only access to the bed, unless the cover is partially removed or the cap has openable side windows.
Rather than using a cap or cover to enclose the entire cargo bed, some pick-up owners/operators prefer an enclosed storage compartment that is mounted in a portion of the bed, leaving the rest of the bed open. Various designs of bed-carried storage units have been proposed and sold commercially, most being configured to contain and protect small objects such as tools.
One general type of storage unit is mounted at the extreme forward end of the cargo bed and spans the full width of the bed. Doors are typically provided on the top of the unit and open upwardly. These units usually have portions that extends outwardly over the side walls of the bed to engage stake pockets formed in the side walls, and accordingly they prevent simultaneous use of any cover or cap that extends over the full length of the bed. The doors can usually be lifted open by a person standing alongside the vehicle, but access to the interior of the compartment still requires either an awkward reach over the bed side walls or climbing into the bed. Front-mounted storage units also have the drawback of significantly decreasing the usable length of the bed, thus limiting the size of objects that may be carried.
Another type of storage unit is adapted to be positioned at the extreme rear of the bed, adjacent the tail gate, with doors and/or drawers that are openable once the tail gate is lowered. Although such units provide storage that is relatively easily reached when standing behind the truck, they also of necessity obstruct access to the bed forward of the storage unit. These units are similar to the front-mounted units described above in that they often include some structure extending over the top of the sidewalls to hold them in place, and thus are incompatible with bed caps and covers.
Pick-up trucks are also sometimes used to carry bed-mounted camper units. Since a standard camper unit occupies substantially the entire cargo bed, any of the bed-mounted storage units existing in the prior art must be removed before a camper may be mounted. The only spaces within the bed that are of a practically usable size when a camper unit is mounted are the two volumes directly forward of the wheel well housings on either side of the bed. These spaces are left empty because a camper unit is designed to slide horizontally into the mounted position from the rear of the bed, so that the lowermost 18 to 24 inches of the front end of the camper can be no wider than the distance between the wheel well housings. These two volumes are completely boxed-in by the camper unit and the bed side walls and so can not be accessed from the outside of the truck.
Pick-up trucks are also sometimes used to tow so-called "fifth-wheel" trailers. For this task, the truck is fitted with a large towing hitch on the floor of the bed above the truck's rear axle. While there is room in the bed forward of the hitch to install a storage unit if desired, the fifth-wheel trailer extends forwardly of the hitch to overhang any storage unit located there and obstruct opening of the unit's doors.